XROOTD: Fix memory leak in case proc files can not be opened for writing server statistics

xrootd/XrdxCastor2Proc.cpp

@@ -84,6 +84,8 @@ XrdxCastor2Proc::Handle( const char* name )
       files.Add( name, phandle );
       return phandle;
     }
+
+    delete phandle;
   }
 
   return NULL;